U.S. patent application number 11/890142 was filed with the patent office on 2008-02-07 for ink-jet printer.
This patent application is currently assigned to Brother Kogyo Kabushiki Kaisha. Invention is credited to Yasunari YOSHIDA.
Application Number | 20080030563 11/890142 |
Document ID | / |
Family ID | 39028712 |
Filed Date | 2008-02-07 |
United States Patent
Application |
20080030563 |
Kind Code |
A1 |
YOSHIDA; Yasunari |
February 7, 2008 |
Ink-jet printer
Abstract
An ink-jet printer, including a feeding mechanism which feeds a
recording medium in a feeding direction; an ink-jet head which
ejects ink onto a surface of the recording medium at a recording
position where the ink-jet head faces the recording medium fed by
the feeding mechanism in the feeding direction; a pressing device
including at least one spur and pressing the surface of the
recording medium on a downstream side of the recording position in
the feeding direction by bringing at least one of the at least one
spur into contact with the surface of the recording medium; and a
pressing-position-changing mechanism which selectively realizes one
of a plurality of states which are different from each other in at
least one pressing position, in the feeding direction, at which the
pressing device presses the surface of the recording medium.
Inventors: |
YOSHIDA; Yasunari;
(Aichi-ken, JP) |
Correspondence
Address: |
REED SMITH, LLP;ATTN: PATENT RECORDS DEPARTMENT
599 LEXINGTON AVENUE, 29TH FLOOR
NEW YORK
NY
10022-7650
US
|
Assignee: |
Brother Kogyo Kabushiki
Kaisha
|
Family ID: |
39028712 |
Appl. No.: |
11/890142 |
Filed: |
August 3, 2007 |
Current U.S.
Class: |
347/104 |
Current CPC
Class: |
B41J 11/0005 20130101;
B41J 13/025 20130101 |
Class at
Publication: |
347/104 |
International
Class: |
B41J 2/01 20060101
B41J002/01 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 3, 2006 |
JP |
2006-212129 |
Claims
1. An ink-jet printer, comprising: a feeding mechanism which feeds
a recording medium in a feeding direction; an ink-jet head which
ejects ink onto a surface of the recording medium at a recording
position where the ink-jet head faces the recording medium fed by
the feeding mechanism in the feeding direction; a pressing device
including at least one spur and pressing the surface of the
recording medium on a downstream side of the recording position in
the feeding direction by bringing at least one of the at least one
spur into contact with the surface of the recording medium; and a
pressing-position-changing mechanism which selectively realizes one
of a plurality of states which are different from each other in at
least one pressing position, in the feeding direction, at which the
pressing device presses the surface of the recording medium.
2. The ink-jet printer according to claim 1, wherein the
pressing-position-changing mechanism is configured to selectively
realize one of (a) a first state, as one of the plurality of
states, in which the pressing device presses the surface of the
recording medium at a first position and does not press the surface
of the recording medium on an upstream side of the first position
in the feeding direction, and (b) a second state, as one of the
plurality of states, in which the pressing device presses the
surface of the recording medium at least at a second position
located on the upstream side of the first position in the feeding
direction.
3. The ink-jet printer according to claim 2, wherein the pressing
device includes a plurality of spurs as the at least one spur,
wherein the plurality of spurs includes at least one first spur
capable of contacting the surface of the recording medium at the
first position and at least one second spur capable of contacting
the surface of the recording medium at the second position, and
wherein the pressing-position-changing mechanism is configured to
realize (a) the first state by allowing the at least one first spur
to contact the surface of the recording medium and by inhibiting
the at least one second spur from contacting the surface of the
recording medium, and (b) the second state by allowing at least the
at least one second spur to contact the surface of the recording
medium.
4. The ink-jet printer according to claim 3, wherein a number of
the at least one second spur is greater than that of the at least
one first spur.
5. The ink-jet printer according to claim 3, wherein the
pressing-position-changing mechanism is configured to realize (a)
the first state by allowing the at least one first spur to contact
the surface of the recording medium and by inhibiting the at least
one second spur from contacting the surface of the recording
medium, and (b) the second state by allowing the at least one
second spur to contact the surface of the recording medium and by
inhibiting the at least one first spur from contacting the surface
of the recording medium.
6. The ink-jet printer according to claim 2, wherein the at least
one spur is movable and wherein the pressing-position-changing
mechanism is configured to realize (a) the first state by
positioning the at least one spur to a position in which the at
least one spur is allowed to contact the surface of the recording
medium at the first position, and (b) the second state by
positioning the at least one spur to a position in which the at
least one spur is allowed to contact the surface of the recording
medium at the second position.
7. The ink-jet printer according to claim 2, wherein the
pressing-position-changing mechanism is configured to realize the
first state in a case where a type of the recording medium is a
glossy paper sheet, and to realize the second state in a case where
the type of the recording medium is a plain paper sheet which has a
lower gloss than the glossy paper sheet.
8. The ink-jet printer according to claim 2, wherein the
pressing-position-changing mechanism is configured to realize the
first state in a case where a type of the recording medium is a
thick paper sheet having a thickness larger than a predetermined
thickness, and to realize the second state in a case where the type
of the recording medium is a thin paper sheet having a thickness
smaller than the predetermined thickness.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority from Japanese Patent
Application No. 2006-212129, which was filed on Aug. 3, 2006, the
disclosure of which is herein incorporated by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an inkjet printer including
a head which ejects ink onto a recording medium and a feeding
mechanism which feeds the recording medium through a position
opposed to the head.
[0004] 2. Description of the Related Art
[0005] There is conventionally known the ink-jet printer including
the head which ejects the ink onto the recording medium and the
feeding mechanism which feeds the recording medium through a
recording position where the ink ejected from the head can be
applied to the recording medium. In this kind of ink-jet printer,
when the recording medium is fed through the recording position,
the ink is ejected onto a surface of the recording medium from the
head, thereby forming desired image on the recording medium.
[0006] In addition, in this kind of inkjet printer, in order to
prevent a ripple of a sheet, i.e., what is called a cockling, after
the image is formed, it is proposed to provide rowels or spurs for
pressing the surface of the recording medium at a position located
on a downstream side of the recording position in a direction in
which the feeding mechanism feeds the recording medium.
[0007] However, when the ink ejected onto the recording medium
adheres to the spurs and the ink adhering to the spurs adheres to a
surface of a following recording medium fed after the recording
medium, the following recording medium is stained with the ink by
the spurs. To deal with this, it is proposed in J. P. A.
Publication No. 2004-98601 to separate the spurs for preventing the
cockling from the recording medium when forming the image on a
recording medium in which the cockling is relatively less likely to
occur.
SUMMARY OF THE INVENTION
[0008] Unfortunately, if the spurs for preventing the cockling are
completely separated from the recording medium and thereby do not
function at all, a certain degree of the cockling may occur even
though the recording medium in which the cockling is relatively
less likely to occur is used. Thus, the ink may be unevenly applied
to the recording medium, so that quality of the recorded image may
be deteriorated. Therefore, it is an object of the present
invention to provide an ink-jet printer which can satisfactorily
reduce a cockling and an ink stain caused by spurs.
[0009] The object indicated above may be achieved according to the
present invention which provides an ink-jet printer comprising: a
feeding mechanism which feeds a recording medium in a feeding
direction; an ink-jet head which ejects ink onto a surface of the
recording medium at a recording position where the ink-jet head
faces the recording medium fed by the feeding mechanism in the
feeding direction; a pressing device including at least one spur
and pressing the surface of the recording medium on a downstream
side of the recording position in the feeding direction by bringing
at least one of the at least one spur into contact with the surface
of the recording medium; and a pressing-position-changing mechanism
which selectively realizes one of a plurality of states which are
different from each other in at least one pressing position, in the
feeding direction, at which the pressing device presses the surface
of the recording medium.
[0010] In the image recording apparatus constructed as described
above, there is provided the pressing device including at least one
spur and pressing the surface of the recording medium on the
downstream side of the recording position in the feeding direction
by bringing at least one of the at least one spur into contact with
the surface of the recording medium, thereby reducing the cockling
of the recording medium satisfactorily. Further, in the present
invention, the pressing-position-changing mechanism which
selectively realizes one of a plurality of states which are
different from each other in at least one pressing position, in the
feeding direction, at which the pressing device presses the surface
of the recording medium, according to a type of sheet, for example.
Thus, if the pressing-position-changing mechanism is configured to
selectively realize one of a plurality of states according to the
type of sheet, the following effects can be obtained. For a sheet
in which the cockling is relatively more likely to occur, the at
least one of the at least one spur presses the sheet at a position
near to the recording position in the feeding direction, thereby
reducing the cockling. For a sheet in which the cockling is
relatively less likely to occur, the at least one of the at least
one spur presses the sheet at a position distant from the recording
position in the feeding direction, whereby the ink stain by the at
least one of the at least one spur can be reduced. Thus, in the
present invention, at least one of the at least one spur for
preventing the cockling is used such that a position thereof is
changed for the sheet in which the cockling is relatively more
likely to occur and for the sheet in which the cockling is
relatively less likely to occur, thereby reducing the cockling more
satisfactorily in comparison with a case in which spurs for
preventing the cockling are switched between a state thereof in
which the spurs are used and a state thereof in which the spurs are
disused.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The above and other objects, features, advantages, and
technical and industrial significance of the present invention will
be better understood by reading the following detailed description
of preferred embodiments of the invention, when considered in
connection with the accompanying drawings, in which:
[0012] FIG. 1 is an external perspective view of an inkjet printer
as an embodiment of the present invention,
[0013] FIG. 2 is a side elevational view in cross section showing
an internal structure of the ink-jet printer,
[0014] FIGS. 3A and 3B are views for explaining a structure of an
image forming unit which is a part of the internal structure of the
ink-jet printer,
[0015] FIG. 4 is a top view schematically showing the structure of
the image forming unit,
[0016] FIGS. 5A and 5B are views for explaining a structure of a
spur-moving mechanism of the image forming unit,
[0017] FIG. 6 is a block diagram showing a configuration of a
control system of the ink-jet printer,
[0018] FIG. 7 is a flow chart representing a printing operation
performed by the control system,
[0019] FIGS. 8A and 8B are views for explaining a structure of a
modified example of the spur-moving mechanism,
[0020] FIGS. 9A and 9B are views for explaining a structure of
another modified example of the spur-moving mechanism,
[0021] FIG. 10 is a flow chart representing a modified example of
the printing operation.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] Hereinafter, there will be described preferred embodiments
of the present invention by reference to the drawings. It is to be
understood that the following embodiments are described only by way
of example, and the invention may be otherwise embodied with
various modifications without departing from the scope and spirit
of the invention. FIG. 1 is an external perspective view of an
ink-jet printer 1 to which the present invention is applied, and
FIG. 2 is a side elevational view in cross section showing an
arrangement of components accommodated in a main casing 2 of the
ink-jet printer 1 but a part of the components such as a scanner
unit 20 described below which are disposed in an upper portion of
the ink-jet printer 1 are not shown. It is noted that, in the
following description, there will be used terms "upper", "lower",
"right", "left", "front", and "rear" directions of the ink-jet
printer 1 that are indicated by respective arrows "TOP", "BOTTOM",
"RIGHT", "LEFT", "FRONT", and "REAR" in FIG. 1 which shows a
normally used state of the ink-jet printer 1. That is, an operation
panel 10 described below is provided in a front portion of the
ink-jet printer 1. Right and left portions of the ink-jet printer 1
are located in right and left sides, respectively, as seen from a
user who is in a front side of the ink-jet printer 1.
<Explanation of Overall Structure of the Ink-Jet Printer>
[0023] The ink-jet printer 1 as the present embodiment is what is
called a composite machine having a printing function, a scanning
function, a color copying function, a facsimile function, and so
on, and as shown in FIG. 1, an exterior of the ink-jet printer 1 is
constituted by the main casing 2 which is formed of a synthetic
resin and has a rectangular boxlike shape.
[0024] On a front portion of an upper surface of the main casing 2,
there is provided the operating panel 10 which includes an
operating portion 11 on which various operating buttons for an
inputting operation are disposed and a display portion 12 (e.g., a
crystal liquid display) on which images such as messages are
displayed. Further, at a rear of the operating panel 10, the
scanner unit 20 which reads an image from a document is provided.
It is noted that the scanner unit 20 is used for the scanning
function, the color copying function, and the facsimile
function.
[0025] On the other hand, in a lower portion of an inside of the
main casing 2, as shown in FIG. 2, there is provided a sheet-supply
tray 30 which can accommodate a plurality of sheet-like recording
media, such as paper sheets or plastic sheets, stacked (superposed)
on one another, such that each of the recording media takes a
substantially horizontal posture. It is noted that the sheet-supply
tray 30 is detachable from the main easing 2 by being horizontally
withdrawn toward the front through an opening 2a (as shown in FIG.
1) formed in a front surface of the main casing 2, and in contrast,
the sheet-supply tray 30 is attachable to the main casing 2 by
being horizontally inserted through the opening 2a of the main
casing 2.
[0026] In a rear portion of the inside of the main casing 2 and
above the sheet-supply tray 30, there is provided a frame 4 which
is formed of metal and has a box-like shape elongating in the
rightward and leftward direction. The sheet-supply unit 50 is
supported by the frame 4 so as to be disposed above a rear end
portion of the sheet-supply tray 30, and has a sheet-supply roller
60 for supplying (feeding) the recording media accommodated in the
sheet-supply tray 30, one by one, to a sheet-feed path 5 provided
at a rear of the sheet-supply tray 30. That is, in a rear end
portion of the inside of the main casing 2, there is formed the
sheet-feed path 5 through which each recording medium fed
rearwardly from the sheet-supply tray 30 makes an upward U-turn and
is guided frontward. Above the sheet-supply unit 50, there is
disposed an image forming unit 70 which forms an image on the
recording medium fed while guided by the sheet-feed path 5. The
recording medium on which the image is recorded in the image
forming unit 70 is discharged onto a front portion of an upper
surface of the sheet-supply tray 30.
<Structure of the Image Forming Unit>
[0027] There will be next explained a structure of the image
forming unit 70. FIGS. 3A and 5B are views for schematically
explaining the structure of the image forming unit 70. As shown in
FIGS. 2, 3A, and 3B, the image forming unit 70 includes a
sheet-feed roller 71 provided at a positon, in the sheet-feed path
5, where the recording medium fed from the sheet-supply tray 30 is
reached after making the upward U-turn. The sheet-feed roller 71 is
supported by side plates of the frame 4 so as to be rotatable about
a rotating shaft thereof extending in the leftward and rightward
direction. It is noted that the sheet-feed roller 71 is driven to
be rotated by a sheet-feed motor 131 (as shown in FIG. 6). In
addition, under the sheet-feed roller 71, there is provided a
driven roller 72 which is rotatable about a rotating shaft thereof
extending parallel to that of the sheet-feed roller 71 and driven
by the same 71 to be rotated. That is, the sheet-feed roller 71 and
the driven roller 72 are configured as a pair of rollers.
[0028] Further, the image forming unit 70 includes a recording head
73 which is mounted on a carriage (not shown), which is moved in
the leftward and rightward direction (i.e., a main scanning
direction), and which is capable of ejecting inks of a plurality of
colors from nozzles formed in a lower surface of the recording head
73. In the image forming unit 70, in front of the driven roller 72,
i.e., on a downstream side of the driven roller 72 in a sheet
feeding direction in which the recording medium is fed, there is
provided a platen 74A which supports the recording medium at a
recording position where the ink ejected from the recording head 73
can be applied to the recording medium. A carriage motor 133 (as
shown in FIG. 6) is driven so as to move the recording head 73,
integrally with the carriage, in the main scanning direction, and
the inks are ejected from the recording head 73 onto the recording
medium on the platen 74A, whereby an image is formed on the
recording medium.
[0029] Additionally, in front of the recording head 73, i.e., on a
downstream side of the recording position in the sheet feeding
direction, the image forming unit 70 includes, above a front end
portion of a platen member 74, a group of spurs 75 and a group of
spurs 76, for preventing a cockling, which are capable of
contacting and pressing the recording medium. The platen member 74
is formed of synthetic resin and provided with the platen 74A
formed on a part of an upper surface of the platen member 74. As
shown in FIGS. 3A and 3B, the spurs 75, 76 are configured such that
only ones of the spurs 75 and the spurs 76 are moved to a vertical
position at which the ones of the spurs 75 and the spurs 76 press
the recording medium (hereinafter, referred to as a "predetermined
lower position"). Meanwhile, the others of the spurs 75 and the
spurs 76 are placed at a vertical position which is located over
the predetermined lower position and at which the others of the
spurs 75 and the spurs 76 do not press the recording medium
(hereinafter, referred to as a "retracted upper position"). The
placements of the spurs 75, 76 in the predetermined lower position
or the retracted upper position are made by a spur-moving mechanism
80 described below. Further, in front of the platen member 74,
there are provided a sheet-discharge roller 77 which is driven by
the sheet-feed motor 131 (as shown in FIG. 6) and a group of spurs
78, for discharging the recording medium, which are driven to be
rotated by the sheet-discharge roller 77.
[0030] As shown in FIG. 4, the spurs 75, the spurs 76, and the
spurs 78 are provided, at respective constant intervals in the
leftward and rightward direction, on respective rotating shafts
75A, 76A, 78A extending in the leftward and rightward direction.
Numbers of the spurs 75, the spurs 76, and the spurs 78 are
different from each other, that is, seven spurs 75, six spurs 76,
and four spurs 78 are provided. Further, at a right end of a range
in which the recording head 73 is moved in the main scanning
direction, that is, outside a sheet-feed area in which the
recording medium is fed, there are provided various maintenance
mechanisms such as a cap 79 which fluid-tightly closes a lower
surface of the recording head 73 to suck the ink and the like from
the nozzles. When the recording head 73 is located inside the
sheet-feed area, as described above, a drive force of the
sheet-feed motor 131 (as shown in FIG. 6) is transmitted to a
driving system, including the sheet-feed roller 71 and the
sheet-discharge roller 77, which is driven to feed the recording
medium. When the recording head 73 is moved to a right side of the
sheet-feed area, the drive force of the sheet-feed motor 131 is
transmitted to the maintenance mechanisms via a clutch mechanism
(not shown). Furthermore, when the recording head 73 is moved to a
home position thereof located a left side of the sheet-feed area,
the drive force of the sheet-feed motor 131 is transmitted to a
gear 81 of the spur-moving mechanism 80 as shown in FIGS. 5A and
5B.
[0031] The spur-moving mechanism 80 includes a cam 83 which is
moved in the frontward and rearward direction as shown in FIGS. 5A
and 513 by a rotation of the gear 81. The gear 81 serving as a
pinion meshes with toothed surface of the cam 83 serving as a rack.
A cam surface 83A is provided by an upper surface of the cam 83
pushes up one of rotating shafts 75A, 76A, whereby the only ones of
the spurs 75 and the spurs 76 press the recording medium as
described above. That is, as shown in FIG. 5A, when the cam 83 is
moved frontward and the cam surface 83A pushes up the rotating
shaft 76A, as shown in FIG. 3B, only the spurs 75 are moved to the
predetermined lower position and press the recording medium, while
the spurs 76 are moved to the retracted upper position and
separated from the recording medium. In contrast, as shown in FIG.
5B, when the cam 83 is moved rearward and the cam surface 83A
pushes up the rotating shaft 75A, as shown in FIG. 3A, only the
spurs 76 are moved to the predetermined lower position and press
the recording medium, while the spurs 75 are moved to the retracted
upper position and separated from the recording medium. In
addition, stoppers and the like (not shown) are further provided in
mechanisms for supporting the spurs 75, 76. The rotating shafts
75A, 75B are supported by the stoppers such that the spurs 75, 76
are prevented from moving to a position lower than a position
indicated by dot lines in FIGS. 3A and 3B.
[0032] In the image recording apparatus constructed as described
above, it is considered that there is provided a pressing device
including at least one spur and pressing the surface of the
recording medium on a downstream side of the recording position in
the sheet feeding direction by bringing at least one of the at
least one spur into contact with the surface of the recording
medium, and a pressing-position-changing mechanism which
selectively realizes one of a plurality of states which are
different from each other in at least one pressing position, in the
sheet feeding direction, at which the pressing device presses the
surface of the recording medium. More specifically, the
pressing-position-changing mechanism is configured to selectively
realize one of (a) a first state, as one of the plurality of
states, in which the pressing device presses the surface of the
recording medium at a first position and does not press the surface
of the recording medium on an upstream side of the first position
in the sheet feeding direction, and (b) a second state, as one of
the plurality of states, in which the pressing device presses the
surface of the recording medium at least at a second position
located on the upstream side of the first position in the sheet
feeding direction. Described in more detail, the pressing device
includes a plurality of spurs as the at least one spur. The
plurality of spurs includes at least one first spur capable of
contacting the surface of the recording medium at the first
position and at least one second spur capable of contacting the
surface of the recording medium at the second position. Further,
the pressing-position-changing mechanism is configured to realize
(a) the first state by allowing the at least one first spur to
contact the surface of the recording medium and by inhibiting the
at least one second spur from contacting the surface of the
recording medium, and (b) the second state by allowing at least the
at least one second spur to contact the surface of the recording
medium. In the above-mentioned embodiment, the spurs 76 corresponds
to the at least one first spur, the spurs 75 corresponds to the at
least one second spur, and the spur-moving mechanism 80 corresponds
to the pressing-position-changing mechanism.
<Configuration and Control of Control System of the Ink-Jet
Printer>
[0033] Next, as shown in FIG. 6, the ink-jet printer 1 includes a
control section 90 which controls an entirety of the ink-jet
printer 1. The control section 90 is connected to the operating
panel 10, the recording head 73, the sheet-feed motor 131, and the
carriage motor 133 as described above, and further connected to an
input interface (an input I/F) 135 to which various data are
inputted from a personal computer (hereinafter, referred to as a
PC, not shown) as a host device. It is noted that the control
section 90 is connected to not only the components described above
but also various sensors, actuators, and the like, but only
components relating to a following description are shown in FIG.
6.
[0034] Further, as shown in FIG. 6, the control section 90 is
configured as a microcomputer including a CPU 91, a ROM 93, and a
RAM 95. When a printing command is inputted to the input interface
135 from the PC, the control section 90 performs a printing
operation shown in FIG. 7 on the basis of a software program stored
in the ROM 93.
[0035] FIG. 7 is a flow chart representing the printing operation.
As shown in FIG. 7, upon starting the printing operation, first in
Step S1 (hereinafter, "Step" is omitted where appropriate),
printing conditions set in a printer driver of the PC are read. In
following S2, a type of the recording medium set in the printing
conditions is judged. If it is judged, in S2, that the type of the
recording medium is a plain paper sheet, the operation goes to S3
in which the spurs 75 and the spurs 76 are moved as follows. That
is, because the recording head 73 is located in the home position
thereof at the beginning of the operation, the sheet-feed motor 131
is driven in this state of the recording head 73, thereby rotating
the gear 81. The cam 83 is thus moved by the gear 81 to a position
indicated by FIG. 5A. As a result, as indicated by solid lines in
FIG. 5B, the spurs 76 for a glossy paper sheet are moved to the
retracted upper position, while the spurs 75 for the plain paper
sheet are moved to the predetermined lower position where the spurs
75 can contact the recording medium. In other words, the
spur-moving mechanism 80 is configured to realize the first state
in a case where the type of the recording medium is the glossy
paper sheet, and to realize the second state in a case where the
type of the recording medium is the plain paper sheet.
[0036] In S4, the sheet-feed motor 131 is further driven in a state
in which the recording head 73 has been moved to the sheet-feed
area, whereby a process for supplying the recording medium is
carried out, i.e., the recording medium is supplied by the
sheet-supply roller 60 and the sheet-feed roller 71. In S5, the
recording medium is further fed, and the carriage motor 133 and the
recording head 73 are driven, whereby a process for printing is
carried out, i.e., an image based on printing data inputted from
the PC is formed on the recording medium. In S6, a process for
discharging the recording medium is carried out, i.e., the
recording medium is discharged by the sheet-discharge roller 77. In
S7, it is judged whether a job based on the printing data is
completed or not. If the job is not completed (S7: N), the steps
S4-S6 are repeated. If the job is completed (S7: Y), the present
printing operation is completed as well.
[0037] On the other hand, if it is judged, in S2, that the type of
the recording medium is the glossy paper sheet or a matte paper
sheet, the operation goes to S8 in which the spurs 75 and the spurs
76 are moved as follows, and then goes to S4 described above. That
is, in S8, the sheet-feed motor 131 is driven with the recording
head 73 located in the home position thereof as described above,
whereby the cam 83 is moved to a position thereof indicated by FIG.
5B. As a result, as indicated by solid lines in FIG. 3A, the spurs
75 for the plain paper sheet are moved to the retracted upper
position, while the spurs 76 for the glossy paper sheet are moved
to the predetermined lower position where the spurs 76 can contact
the recording medium. As described above, the pressing position of
the pressing device including the spurs 75, 76 is changed by
control of the control section 90. Thus, in this ink-jet pritner 1,
the above-described pressing-position-changing mechanism can be
considered to be configured to include a portion of the control
section 90 which controls to perform the steps S2, S3, and S8.
Effects of the Embodiment of the Present Invention
[0038] Therefore, in this ink-jet printer 1, for the plain paper
sheet in which the cockling is relatively more likely to occur, the
spurs 75 press the recording medium at a position near to the
recording position, in the feeding direction, where the ink ejected
from the recording head 73 can be applied to the recording medium,
thereby reducing the cockling. For the glossy paper sheet or the
matte paper sheet in which the cockling is relatively less likely
to occur and which is relatively more likely to be stained with the
ink by the spurs, the spurs 76 press the sheet at a position
distant from the recording position in the sheet feeding direction,
whereby the ink stain by the spurs can be reduced. In addition, in
this ink-jet printer 1, the ones of the spurs 75 and the spurs 76
are used for preventing the cockling, thereby reducing the cockling
more satisfactorily in comparison with the case in which spurs for
preventing the cockling are switched between a state thereof in
which the spurs are used and a state thereof in which the spurs are
disused.
[0039] Further, in this ink-jet printer 1, the spurs 75 for the
plain paper sheet and the spurs 76 for the glossy paper sheet are
provided independently of each other, so that the following
additional effects are obtained. That is, for the plain paper
sheet, a pigment ink easily adhering to spurs is often used. On the
other hand, for the glossy paper sheet, an image is often formed at
a high resolution, so that a request preventing the ink stain by
the spurs is even stronger. In addition, each of the glossy paper
sheet and the matte paper sheet has a large thickness, so that the
sheet is easily stained with the ink by the spurs. To deal with
this, in this ink-jet printer 1, the spurs 75 for the plain paper
sheet and the spurs 76 for the glossy paper sheet are provided
independently of each other. Thus, the pigment ink adhering to the
spurs 75 when an image is formed on the plain paper sheet with the
pigment ink can be prevented from adhering to the glossy paper
sheet on which an image is formed at the high resolution.
[0040] In addition, in this ink-jet printer 1, a number of the
spurs 75 for the plain paper sheet is greater than that of the
spurs 76 for the glossy paper sheet. Thus, for the plain paper
sheet in which the cockling is more likely to occur, a relatively
large number of the spurs 75 press the sheet, thereby reducing the
cockling more satisfactorily. For the glossy paper sheet or the
matte paper sheet in which the cockling is relatively less likely
to occur and which are relatively more likely to be stained with
the ink by the spurs, a relatively small number of the spurs 76
press the sheet, thereby reducing the ink stain by the spurs more
satisfactorily.
[0041] It is noted that, in this inkjet printer 1, if the cam 83 is
further moved frontward from a position thereof indicated by the
FIG. 5A, both of the spurs 75 and the spurs 76 are moved to the
predetermined lower position, whereby the both of the spurs 75 and
the spurs 76 can press the recording medium. In addition, if the
cam surface 83A is provided such that a portion thereof projecting
upward is long enough, the both of the spurs 75 and the spurs 76
can be moved to the retracted upper position.
MODIFIED EXAMPLES OF THE EMBODIMENT OF THE PRESENT INVENTION
[0042] There will be next explained modified examples of the
spur-moving mechanism 80 as the pressing-position-changing
mechanism. In a spur-moving mechanism 180 shown in FIGS. 8A and 8B,
there are provided spur holders 182, 183 sandwiching a gear 181
from the rear and the front, respectively, which gear 181 is driven
as well as the gear 81. In the spur holder 182, there is formed a
through hole 182A which elongates in the upward and downward
direction and which is open through in the leftward and rightward
direction. The rotating shaft 75A on which the spurs 75 are
provided is inserted into the through hole 182A, such that the
rotating shaft 75A is rotatable and movable in the upward and
downward direction in the through hole 182A. Similarly, in the spur
holder 183, there is formed a through hole 183A which elongates in
the upward and downward direction and which is open through in the
leftward and rightward direction. The rotating shaft 76A on which
the spurs 76 are provided is inserted into the through hole 183A,
such that the rotating shaft 76A is rotatable and movable in the
upward and downward direction in the through hole 183A. It is noted
that the rotating shafts 75A, 76A are downwardly biased toward
respective lower ends of the through holes 182A, 183A by respective
springs (not shown).
[0043] In addition, the spur holders 182, 183 and the gear 181 are
engaged with each other in a state in which the spur holders 182,
183 sandwich the gear 181 from the rear and the front,
respectively, as described above. The gear 181 serving as a pinion
meshes with toothed surfaces of the respective spur holders 182,
183 serving as racks. Thus, when the gear 181 is rotated in a
clockwise direction in FIGS. 8A and 8B, the spur holder 182 is
moved downward, and the spur holder 183 is moved upward. As a
result, as shown in FIG. 5B, the spurs 75 can be placed at the
predetermined lower position defined by the above-described
stoppers, and the spurs 76 can be placed at the retracted upper
position. In contrast, when the gear 181 is rotated in a
counterclockwise direction in FIGS. 8A and 8B, the spur holder 182
is moved upward, and the spur holder 183 is moved downward. As a
result, as shown in FIG. 3A, the spurs 75 can be placed at the
retracted upper position, and the spurs 76 can be placed at the
predetermined lower position. Consequently, if the spur-moving
mechanism 180 is employed, the same actions and effects as the
above-described embodiment are obtained as well.
[0044] It is noted that, in this ink-jet printer 1, when each one
of the spur holders 182, 183 is moved downward, the lower end of a
corresponding one of the through holes 182A, 183A is placed at a
position which is much lower than a position where the stoppers are
located. Consequently, if the spur holders 182, 183 are placed such
that height positions of the spur holders 182, 183 are
approximately the same, the both of the spurs 75 and the spurs 76
are placed at the predetermined lower position, thereby pressing
the recording medium.
[0045] Next, a spur-moving mechanism 280 shown in FIGS. 9A and 9B
includes a bearing member 283 which is moved in the frontward and
rearward direction, as well as the cam 83, by a rotation of a gear
281 driven as well as the above-mentioned gear 81. The bearing
member 283 supports the rotating shaft 75A such that the rotating
shaft 75A is rotatable and movable integrally with the bearing
member 283. In addition, in this inkjet printer 1, the spurs 76 are
not provided. In the spur-moving mechanism 280 thus configured, the
spurs 75 are moved in the frontward and rearward direction, thereby
changing positions at which the spurs 75 press the recording
medium. In other words, the spur-moving mechanism 280 is configured
to realize (a) the first state by positioning the spurs 75 to
positions in which the spurs 75 are allowed to contact the surface
of the recording medium at the first position, and (b) the second
state by positioning the spurs 75 to positions in which the spurs
75 are allowed to contact the surface of the recording medium at
the second position. Thus, in this inkjet printer 1, for the plain
paper sheet in which the cockling is relatively more likely to
occur, the spurs 75 are placed at the position near to the
recording position in the sheet feeding direction, thereby reducing
the cockling. For the glossy paper sheet or the matte paper sheet
in which the cockling is relatively less likely to occur and which
is more likely to be stained with the ink by the spurs, the spurs
75 are placed at the position distant from the recording position
in the sheet feeding direction, thereby reducing the ink stain by
the spurs. In addition, if the spur-moving mechanism 280 is
employed, the above-described effects obtained by providing the
spurs 75 for the plain paper sheet and the spurs 76 for the glossy
paper sheet independently of each other are not obtained, but fewer
components of the image forming unit 70 and the spur-moving
mechanism 80 can be used, thereby reducing a manufacturing cost of
the ink-jet printer 1, in comparison with the above-mentioned
embodiments.
[0046] In addition, the present invention is not limited to the
above-described embodiments, but may be embodied with various
changes and modifications without departing from the spirit and
scope of the present invention. For example, the present invention
may be modified as follows. That is, the cockling is more likely to
occur in a thin paper sheet, and is less likely to occur in a thick
paper sheet. Further, the thin paper sheet has low rigidity, and
the thick paper sheet has high rigidity. Thus, a higher pressure is
applied to the thick paper sheet than the thin paper sheet when the
spurs contact the recording medium, so that the thick paper sheet
is more likely to be stained with the ink than the thin paper
sheet. To deal with this, the operation of FIG. 10 may be
substituted for that of FIG. 7. It is noted that because the
operation of FIG. 10 is different from that of FIG. 7 only in a way
in which S102, S103, and S108 of the FIG. 10 are substituted for
S2, S3, and S8 of the FIG. 7, respectively, there will be explained
only these differences.
[0047] In S102 substituted for S2, it is judged that the type of
the recording medium set in the printing conditions is the thick
paper sheet having a thickness larger than a predetermined
thickness or the thin paper sheet having a thickness smaller than
the predetermined thickness. If it is judged, in S102, that the
type of the recording medium is the thin paper sheet, the spurs 75
and the spurs 76 are moved as follows in S103. That is, as
indicated by the solid lines in FIG. 3B, the spurs 76 for the thick
paper sheet are moved to the retracted upper position, while the
spurs 75 for the thin paper sheet are moved to the predetermined
lower position where the spurs 75 can contact the recording
medium.
[0048] In contrast, if it is judged, in S102, that the type of the
recording medium is the thick paper sheet, the spurs 75 and the
spurs 76 are moved as follows in S108. That is, as indicated by the
solid lines in FIG. 3A, the spurs 75 for the thin paper sheet are
moved to the retracted upper position, while the spurs 76 for the
thick paper sheet are moved to the predetermined lower position
where the spurs 76 can contact the recording medium. That is, the
spur-moving mechanism 80 is configured to realize the first state
in a case where the type of the recording medium is the thick paper
sheet having a thickness larger than the predetermined thickness,
and to realize the second state in a case where the type of the
recording medium is the thin paper sheet having a thickness smaller
than the predetermined thickness.
[0049] In the operation of FIG. 10, for the thin paper sheet which
is relatively less likely to be stained with the ink and in which
the cockling are relatively more likely to occur, the spurs 75
press the recording medium at the position near to the recording
position, thereby reducing the cockling. For the thick paper sheet
which is relatively more likely to be stained with the ink and in
which the cockling are relatively less likely to occur, the spurs
76 press the recording medium at the position distant from the
recording position, thereby reducing the ink stain by the spurs. As
described above, the pressing position of the pressing device
including the spurs 75, 76 is changed by control of the control
section 90. Thus, in this ink-jet pritner 1, the above-described
pressing-position-changing mechanism can be considered to be
configured to include a portion of the control section 90 which
controls to perform the steps S102, S103, and S108.
[0050] Further, in the above-described embodiments, the present
invention is applied to what is called a serial-type printer in
which the recording head 73 is moved in the main scanning
direction, but may be applied as well to what is called a line-type
printer in which the nozzles are aligned in the main scanning
direction. In addition, a driving source of the gear 81, (181),
(281) is not limited to the sheet-feed motor 131, but a motor
exclusively used for the gear 81, (181), (281) may be additionally
provided, for example,
* * * * *